The invention relates to idler sprockets, and more particularly to idler sprockets in a belt drive system.
A belt drive system may comprise two or more pulleys with a belt trained between them. The belt may comprise any profile known in the art, including toothed, multi-ribbed or v-belt.
In order to assure proper operation and belt life, a belt tension or preload is applied to the belt. This may be accomplished by simply moving the pulleys slightly apart a predetermined distance. It may also be accomplished by use of a spring loaded tensioner applied to the belt. Another option is to use an adjustable idler sprocket.
In the case of the idler sprocket, the belt tension will be a function of the position of the idler relative to a belt. The idler will also have a belt bearing surface. In the case of an idler sprocket used with synchronous or toothed belts, the idler sprocket belt bearing surface may also comprise teeth. This is particularly the case where the idler sprocket bears on the toothed side of the belt.
During operation the toothed idler sprocket generates noise due to the impact of the sprocket teeth on the belt as the sprocket turns. This noise can be very objectionable.
Representative of the art is Japanese Application No. 09220821 A to Ricoh Co. Ltd which discloses setting a position where each tooth of n (integer of 2 or more) timing belts starts to mesh with a tooth groove of a drive pulley in such a way that it is deviated in the peripheral direction by 1/n of a pitch of a tooth of the drive pulley.
What is needed is a sprocket with significantly reduced operating noise. What is needed is a sprocket having an arcuate pitch that substantially matches the pitch of a belt engaged with a sprocket. What is needed is a sprocket for use with a belt having a minimal wrap angle. The present invention meets these needs.
The primary aspect of the invention is to provide a sprocket with significantly reduced operating noise.
Another aspect of the invention is to provide a sprocket having an arcuate pitch that substantially matches the pitch of a belt engaged with a sprocket.
Another aspect of the invention is to provide a sprocket for use with a belt having a minimal wrap angle.
Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.
The invention comprises a belt drive system and toothed idler sprocket having an arcuate pitch to significantly reduce noise. The toothed idler sprocket having a pitch sufficient to cause proper engagement between a belt and the sprocket at a minimal belt wrap angle.